Tuyere systems are used to inject or blow gases into metallurgical converters containing molten metal to enhance refining of the metal. The gases enter into the converter through a tuyere pipe which over a course of time may become clogged with residue and accumulations which impede flow of gas into the converter. It has been the practice to remove the accumulations from the the tuyere pipe by running a plunger rod through the pipe with the rod entering the pipe through a gas seal and silencer structure connected to the pipe. A check valve is associated with the gas seal structure to prevent blow-back through the gas seal under normal operating conditions when the punch rod is not inserted into the tuyere pipe. The check valve is adapted to be moved to the open position by contact with the punch rod when it is inserted through the tuyere pipe.
As the punch rod is inserted through the gas seal to contact the check valve, gas within the tuyere pipe tends to blow back and escape between its seal and the periphery of the punch rod. At the same time material can be ejected with the escaping gas creating dangerous working conditions. Further the escaping gas produces extremely high noise levels which can have an adverse effect on workers within the vicinity of the converting operations.
In addition loss of gas between the sealing means and the outer periphery of the punch rod can result in molten liquid in the converter flowing back through the tuyere pipe where it can solidify and result in a stoppage. Further escaping gas around the sealing means and the consequent drop of pressure within the converter can in some instances result in the converting action becoming dormant.
In an attempt to compensate for loss of gas during tuyere pipe cleaning operations, higher pressures and greater volumes of gas than actually needed in converting operations are forced through the gas inlet pipes feeding into the tuyere pipe resulting in increased costs of operation.
Various designs of gas seals have been proposed in an attempt to overcome the aforementioned problems. See for example the disclosures of U.S. Pat. Nos. 1,517,972 and 4,019,725. Both of these patents disclose gas seal structure utilizing radially movable seal elements which engage and seal with the outer periphery of the shank portion of a punch rod inserted through the tuyere pipe. The radially movable valve elements of the construction of these patents are susceptible to being bent and knocked out of line when the punch rod is inserted into the seal structure unless extreme care is taken to assure that the punch rod is accurately aligned with respect to the valve elements. This requirement for accurate alignment usually required manual insertion of the punch rod and prevented use of apparatus providing mechanical insertion of the rod.
Further many tuyere sealing means and silencers used to date have required punch rods having special configurations in order to assure sealing engagement with valve elements.
It is an object of my invention to provide for a sealing means and silencer which includes guide slots to guide and provide support for individual valve elements so as to assure that the guide elements may be moved radially outwardly of the tuyere sealing means notwithstanding misalignment of a punch rod and to insure that the movable valve elements will not be bent. It is a further object of the invention to provide for a tuyere sealing means having movable valve elements which will closely engage with and seal with the surface of the shank portion of a punch rod where the engaging surface of the valve elements are complementary in shape to the surface of the outer periphery of the rod.